Many of us cannot be certain of accessing clear and running water.
Some of us have Pre-Filters installed on our water purifiers/filters to "catch" most gross contaminants before they reach the main filter element.
All of these "in-line" pre-filters are small, and can require frequent cleaning, which is always a fuss when one least needs it.
Pre-filtering
always extends the life of the main filter element. Sometimes the main filter element can be cleaned; sometimes it must be replaced.
Sometimes a simple bandana can serve but can be a fuss to arrange.
This device
Millbank Bag dates back to at least WW II and seems effective as a Pre-filter. Output can drip into virtually any water receptacle but suggest wide-mouth water containers are more suitable than narrow mouth vessels. Or carry a small funnel. After vessel is filled, either boil, filter/purify, or chemically treat the water as suits.
CAUTION: this device does NOT remove bacteria/viruses from the water. It is a simple
Pre-Filter.
Mark Young (a YouTube person) has reviewed this item
HERE . I recommend all his vids as being well-worth watching.
I have a question submitted to the maker about possibly cold-dyeing the white canvas to less "obtrusive" colors. I suspect that this is possible and will report.
Disclaimer: no financial interest.